elif-http 0.8.8

//! Error handling middleware for HTTP requests
//!
//! Provides comprehensive error handling including panic recovery and error response formatting.

use crate::{
    errors::HttpError,
    middleware::v2::{Middleware, Next, NextFuture},
    request::ElifRequest,
    response::IntoElifResponse,
};
use futures_util::future::FutureExt;

/// Error handling middleware configuration
#[derive(Debug, Clone)]
pub struct ErrorHandlerConfig {
    /// Whether to include panic details in error responses (development only)
    pub include_panic_details: bool,

    /// Whether to log errors
    pub log_errors: bool,
}

impl Default for ErrorHandlerConfig {
    fn default() -> Self {
        Self {
            include_panic_details: cfg!(debug_assertions), // Only in debug builds
            log_errors: true,
        }
    }
}

/// Error handling middleware
#[derive(Debug)]
pub struct ErrorHandlerMiddleware {
    config: ErrorHandlerConfig,
}

impl ErrorHandlerMiddleware {
    /// Create new error handling middleware with default config
    pub fn new() -> Self {
        Self {
            config: ErrorHandlerConfig::default(),
        }
    }

    /// Create with custom configuration
    pub fn with_config(config: ErrorHandlerConfig) -> Self {
        Self { config }
    }

    /// Enable panic details in responses (use only in development)
    pub fn with_panic_details(mut self, include: bool) -> Self {
        self.config.include_panic_details = include;
        self
    }

    /// Enable error logging
    pub fn with_logging(mut self, enable: bool) -> Self {
        self.config.log_errors = enable;
        self
    }
}

impl Default for ErrorHandlerMiddleware {
    fn default() -> Self {
        Self::new()
    }
}

impl Middleware for ErrorHandlerMiddleware {
    fn handle(&self, request: ElifRequest, next: Next) -> NextFuture<'static> {
        let config = self.config.clone();
        Box::pin(async move {
            // The future from `next.run()` might panic, so we catch it.
            // `AssertUnwindSafe` is used because the handler might not be `UnwindSafe`.
            let result = std::panic::AssertUnwindSafe(next.run(request))
                .catch_unwind()
                .await;

            match result {
                Ok(response) => response,
                Err(panic_info) => {
                    // A panic occurred, so we create an error response.
                    let panic_message = if let Some(s) = panic_info.downcast_ref::<String>() {
                        s.clone()
                    } else if let Some(s) = panic_info.downcast_ref::<&str>() {
                        s.to_string()
                    } else {
                        "Unknown panic occurred".to_string()
                    };

                    if config.log_errors {
                        // Using tracing::error for logging panics.
                        tracing::error!("Panic in request handler: {}", panic_message);
                    }

                    let error_message = if config.include_panic_details {
                        format!("Internal server error: {}", panic_message)
                    } else {
                        "Internal server error occurred".to_string()
                    };

                    let http_error = HttpError::internal(error_message);
                    http_error.into_response()
                }
            }
        })
    }

    fn name(&self) -> &'static str {
        "ErrorHandlerMiddleware"
    }
}

/// Helper function to create error handler middleware
pub fn error_handler() -> ErrorHandlerMiddleware {
    ErrorHandlerMiddleware::new()
}

/// Helper function to create error handler middleware with config
pub fn error_handler_with_config(config: ErrorHandlerConfig) -> ErrorHandlerMiddleware {
    ErrorHandlerMiddleware::with_config(config)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{
        middleware::v2::MiddlewarePipelineV2,
        request::ElifMethod,
        response::{headers::ElifHeaderMap, ElifResponse},
    };

    #[tokio::test]
    async fn test_error_handler_config() {
        let config = ErrorHandlerConfig {
            include_panic_details: true,
            log_errors: false,
        };

        assert!(config.include_panic_details);
        assert!(!config.log_errors);
    }

    #[tokio::test]
    async fn test_error_handler_middleware_creation() {
        let middleware = ErrorHandlerMiddleware::new()
            .with_panic_details(true)
            .with_logging(false);

        assert!(middleware.config.include_panic_details);
        assert!(!middleware.config.log_errors);
    }

    #[tokio::test]
    async fn test_error_handler_with_http_error() {
        let middleware = ErrorHandlerMiddleware::new();

        let request = ElifRequest::new(
            ElifMethod::GET,
            "/test".parse().unwrap(),
            ElifHeaderMap::new(),
        );

        let next = crate::middleware::v2::Next::new(|_req| {
            Box::pin(async {
                // Return an error response
                HttpError::bad_request("Test error").into_response()
            })
        });

        let response = middleware.handle(request, next).await;
        assert_eq!(
            response.status_code(),
            crate::response::status::ElifStatusCode::BAD_REQUEST
        );
    }

    #[tokio::test]
    async fn test_error_handler_normal_flow() {
        let middleware = ErrorHandlerMiddleware::new();
        let pipeline = MiddlewarePipelineV2::new().add(middleware);

        let request = ElifRequest::new(
            ElifMethod::GET,
            "/test".parse().unwrap(),
            ElifHeaderMap::new(),
        );

        let response = pipeline
            .execute(request, |_req| {
                Box::pin(async {
                    ElifResponse::ok().json_value(serde_json::json!({
                        "message": "Success"
                    }))
                })
            })
            .await;

        assert_eq!(
            response.status_code(),
            crate::response::status::ElifStatusCode::OK
        );
    }

    #[test]
    fn test_error_handler_config_default() {
        let config = ErrorHandlerConfig::default();

        // Should include panic details only in debug mode
        assert_eq!(config.include_panic_details, cfg!(debug_assertions));
        assert!(config.log_errors);
    }
}